U.S. patent application number 11/015054 was filed with the patent office on 2006-06-22 for safety system architecture for a hydrogen fueling station.
This patent application is currently assigned to Texaco Inc.. Invention is credited to Tonya A. Betts, Masoud Hajiaghajani, Gregory W. Laframboise, Vesna R. Mirkovic, Hongqiao Sun, W. Spencer Wheat.
Application Number | 20060136099 11/015054 |
Document ID | / |
Family ID | 36588381 |
Filed Date | 2006-06-22 |
United States Patent
Application |
20060136099 |
Kind Code |
A1 |
Hajiaghajani; Masoud ; et
al. |
June 22, 2006 |
Safety system architecture for a hydrogen fueling station
Abstract
An apparatus and a method for use in controlling the apparatus
are disclosed. The apparatus includes a purified hydrogen
generator; at least one of a compression unit, a storage unit, and
a dispensing unit; and a system controller. The system controller
is capable of monitoring the operation of the hydrogen generator
and the compression unit, storage unit, or dispensing unit at a
system level and shutting down at least one of hydrogen generator
and the compression unit, storage unit, or dispensing unit upon the
detection of a dangerous condition. The method includes monitoring
the generation of a purified hydrogen stream from a system level;
monitoring the at least one of a compression, a storage, and a
dispensing of the purified hydrogen gas stream from the system
level in concert with monitoring the purified hydrogen gas stream
generation; and shutting down at least one of the purified hydrogen
gas stream generation and the compression, the storage, or the
dispensing upon the detection of a dangerous condition at the
system level.
Inventors: |
Hajiaghajani; Masoud;
(Houston, TX) ; Mirkovic; Vesna R.; (Pearland,
TX) ; Sun; Hongqiao; (Sugar Land, TX) ; Wheat;
W. Spencer; (Missouri City, TX) ; Laframboise;
Gregory W.; (Concord, CA) ; Betts; Tonya A.;
(Houston, TX) |
Correspondence
Address: |
WILLIAMS, MORGAN & AMERSON
10333 RICHMOND, SUITE 1100
HOUSTON
TX
77042
US
|
Assignee: |
Texaco Inc.
San Ramon
CA
|
Family ID: |
36588381 |
Appl. No.: |
11/015054 |
Filed: |
December 17, 2004 |
Current U.S.
Class: |
700/272 |
Current CPC
Class: |
C01B 2203/1633 20130101;
G05B 9/02 20130101; C01B 2203/0405 20130101; C01B 3/34 20130101;
C01B 2203/82 20130101; C01B 3/48 20130101; C01B 2203/0244 20130101;
C01B 2203/1609 20130101; G05B 23/0286 20130101; C01B 2203/043
20130101; C01B 2203/169 20130101; C01B 2203/085 20130101; G05B
23/021 20130101; C01B 2203/1619 20130101; Y02E 60/32 20130101 |
Class at
Publication: |
700/272 |
International
Class: |
G05B 21/00 20060101
G05B021/00 |
Claims
1. An apparatus, comprising: a hydrogen generator; at least one of
a compression unit, a storage unit, and a dispensing unit; and a
system controller capable of monitoring the operation of the
hydrogen generator and the compression unit, storage unit, or
dispensing unit at a system level and shutting down at least one of
hydrogen generator and the compression unit, storage unit, or
dispensing unit upon the detection of a dangerous condition.
2. The apparatus of claim 1, wherein the hydrogen generator
includes a hydrogen purifier capable of purifying a hydrogen
enriched gas stream produced by the hydrogen generator.
3. The apparatus of claim 1, wherein the hydrogen generator
includes a fuel processor or an electrolyzer.
4. The apparatus of claim 2, wherein the hydrogen purifier includes
a pressure swing adsorption unit or a hydrogen-selective
membrane.
5. The apparatus of claim 1, wherein the system controller
comprises a programmable logic controller.
6. The apparatus of claim 1, wherein the hydrogen generator
includes a local controller and the system controller is capable of
monitoring the operation of the hydrogen generator by monitoring an
output of the local controller.
7. The apparatus of claim 6, wherein the compression unit, storage
unit, or dispensing unit includes a second local controller and the
system controller is capable of monitoring the operation of the
compression unit, storage unit, or dispensing unit by monitoring an
output of the second local controller.
8. The apparatus of claim 1, wherein the compression unit, storage
unit, or dispensing unit includes a local controller and the system
controller is capable of monitoring the operation of the
compression unit, storage unit, or dispensing unit by monitoring an
output of the local controller.
9. The apparatus of claim 1, wherein the system controller is
capable of monitoring the operation of the hydrogen generator by
monitoring a plurality of parameters sensed within the hydrogen
generator.
10. The apparatus of claim 9, wherein the system controller is
capable of monitoring the operation of the compression unit,
storage unit, or dispensing unit by monitoring a second plurality
of parameters sensed within the compression unit, storage unit, or
dispensing unit.
11. The apparatus of claim 1, wherein the system controller is
capable of monitoring the operation of the compression unit,
storage unit, or dispensing unit by monitoring a plurality of
parameters sensed within the compression unit, storage unit, or
dispensing unit.
12. The apparatus of claim 1, further comprising a fire alarm
control system capable of monitoring the apparatus for indications
of fire and signaling the same to the system controller.
13. The apparatus of claim 1, wherein the system controller is
further capable of monitoring for at least one of interruptions in
power supply and emergency shut-off signals.
14. The apparatus of claim 1, wherein the hydrogen generator
includes means for purifying a hydrogen enriched gas stream
produced by the hydrogen generator.
15. The apparatus of claim 1, wherein the hydrogen generator
includes means for generating hydrogen.
16. The apparatus of claim 1, wherein the controller comprises
means for controlling the hydrogen generator and at least one of
the compression unit, storage unit, or dispensing unit.
17. The apparatus of claim 1, wherein the hydrogen generator
includes a local means for controlling the hydrogen generator and
the system controller is capable of monitoring the operation of the
hydrogen generator by monitoring an output of the local controlling
means.
18. The apparatus of claim 1, wherein the compression unit, storage
unit, or dispensing unit includes a local means for controlling the
compression unit, storage unit, or dispensing unit and the system
controller is capable of monitoring the operation of the
compression unit, storage unit, or dispensing unit by monitoring an
output of the local controlling means.
19. The apparatus of claim 1, further comprising means for
detecting smoke or flame and signaling the same to the system
controller.
20. An apparatus, comprising: means for generating hydrogen; means
for at least one of compressing, a storing, and dispensing the
hydrogen; and means for monitoring the operation of the hydrogen
generating means and the compressing, storing or dispensing means
and shutting down at least one of hydrogen generating means and the
compressing, storing or dispensing means upon the detection of a
dangerous condition.
21. The apparatus of claim 20, wherein the hydrogen generating
means includes a hydrogen purifier capable of purifying a hydrogen
enriched gas stream produced by the hydrogen generating means.
22. The apparatus of claim 20, wherein the hydrogen generating
means includes a fuel processor or an electrolyzer.
23. The apparatus of claim 20, wherein the monitoring and shutting
down means comprises a programmable logic controller.
24. The apparatus of claim 20, wherein the hydrogen generating
means includes a local controller and the monitoring and shutting
down means is capable of monitoring the operation of the hydrogen
generating means by monitoring an output of the local
controller.
25. The apparatus of claim 20, wherein the compressing, storing or
dispensing means includes a local controller and the monitoring and
shutting down means is capable of monitoring the operation of the
compressing, storing or dispensing means by monitoring an output of
the local controller.
26. The apparatus of claim 20, wherein the monitoring and shutting
down means is capable of monitoring the operation of the hydrogen
generating means by monitoring a plurality of parameters sensed
within the hydrogen generating means.
27. The apparatus of claim 20, wherein the monitoring and shutting
down means is capable of monitoring the operation of the
compressing, storing or dispensing means by monitoring a plurality
of parameters sensed within the compressing, storing or dispensing
means.
28. The apparatus of claim 20, further comprising a fire alarm
control system capable of monitoring the apparatus for indications
of fire and signaling the same to the monitoring and shutting down
means.
29. The apparatus of claim 20, wherein the monitoring and shutting
down means is further capable of monitoring for at least one of
interruptions in power supply and emergency shut-off signals.
30. A method, comprising: monitoring the generation of a hydrogen
stream from a system level; monitoring the at least one of a
compression, a storage, and a dispensing of the hydrogen gas stream
from the system level in concert with monitoring the hydrogen gas
stream generation; and shutting down at least one of the hydrogen
gas stream generation and the compression, the storage, or the
dispensing upon the detection of a dangerous condition at the
system level.
31. The method of claim 30, wherein monitoring the generation of a
hydrogen stream includes monitoring a hydrogen purifier purifying a
hydrogen enriched gas stream.
32. The method of claim 30, wherein monitoring the generation of a
hydrogen stream includes monitoring the operation of a fuel
processor or an electrolyzer.
33. The method of claim 31, wherein monitoring the hydrogen
purifier includes monitoring a pressure swing adsorption unit or a
hydrogen-selective membrane.
34. The method of claim 30, further comprising locally monitoring
the generation of a hydrogen stream and wherein monitoring the
generation of a hydrogen stream at the system level includes
monitoring an output from the local monitoring of the hydrogen
generation.
35. The method of claim 34, further comprising locally monitoring
the at least one of the compression, the storage, and the
dispensing of the hydrogen gas stream and wherein monitoring the at
least one of the compression, the storage, and the dispensing of
the hydrogen gas stream at the system level includes monitoring an
output from the local monitoring of the at least one of the
compression, the storage, and the dispensing of the hydrogen gas
stream.
36. The method of claim 30, further comprising locally monitoring
the at least one of the compression, the storage, and the
dispensing of the hydrogen gas stream and wherein monitoring the at
least one of the compression, the storage, and the dispensing of
the hydrogen gas stream at the system level includes monitoring an
output from the local monitoring of the at least one of the
compression, the storage, and the dispensing of the hydrogen gas
stream.
37. The method of claim 30, wherein monitoring the generation of a
hydrogen stream from the system level includes monitoring a
plurality of parameters sensed within the generation of a hydrogen
stream.
38. The method of claim 37, wherein monitoring the at least one of
the compression, the storage, or the dispensing of the hydrogen gas
stream from the system level includes monitoring a second plurality
of parameters sensed within the compression, the storage, and the
dispensing of the hydrogen gas stream.
39. The method of claim 30, wherein monitoring the at least one of
the compression, the storage, or the dispensing of the hydrogen gas
stream from the system level includes monitoring a second plurality
of parameters sensed within the compression, the storage, and the
dispensing of the hydrogen gas stream.
40. The method of claim 30, further comprising a fire alarm control
system capable of monitoring the method for indications of fire and
signaling the same to the system controller.
41. The method of claim 30, further comprising monitoring for at
least one of interruptions in power supply and emergency shut-off
signals at the system level.
42. The method of claim 30, further comprising monitoring for the
presence of smoke or flame and signaling the same.
43. A hydrogen fueling station, comprising: a hydrogen generator,
including: a fuel processor capable of reforming a fuel into a
hydrogen enriched gas stream; and a pressure swing adsorption unit
capable of purifying the hydrogen enriched gas stream to produce a
purified hydrogen stream; a compression, storage, and dispensing
unit capable of compressing, storing, and dispensing the purified
hydrogen stream; and a system controller capable of monitoring the
operation of the hydrogen generator and the compression, storage,
and dispensing unit at a system level and shutting down at least
one of hydrogen generator and the compression, storage, and
dispensing unit upon the detection of a dangerous condition.
44. The hydrogen fueling station of claim 43, wherein the system
controller comprises a programmable logic controller.
45. The hydrogen fueling station of claim 43, wherein the hydrogen
generator includes a local controller and the system controller is
capable of monitoring the operation of the hydrogen generator by
monitoring an output of the local controller.
46. The hydrogen fueling station of claim 45, wherein the
compression, storage, and dispensing unit includes a second local
controller and the system controller is capable of monitoring the
operation of the compression, storage, and dispensing unit by
monitoring an output of the second local controller.
47. The hydrogen fueling station of claim 43, wherein the
compression, storage, and dispensing unit includes a local
controller and the system controller is capable of monitoring the
operation of the compression, storage, and dispensing unit by
monitoring an output of the local controller.
48. The hydrogen fueling station of claim 43, wherein the system
controller is capable of monitoring the operation of the hydrogen
generator by monitoring a plurality of parameters sensed within the
hydrogen generator.
49. The hydrogen fueling station of claim 48, wherein the system
controller is capable of monitoring the operation of the
compression, storage, and dispensing unit by monitoring a second
plurality of parameters sensed within the compression, storage, and
dispensing unit.
50. The hydrogen fueling station of claim 43, wherein the system
controller is capable of monitoring the operation of the
compression, storage, and dispensing unit by monitoring a plurality
of parameters sensed within the compression, storage, and
dispensing unit.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention is directed to a hydrogen fueling
station, and, more particularly, to a control system for use in a
fuel processor.
[0003] 2. Description of the Related Art
[0004] There are numerous uses for pure hydrogen or
hydrogen-enriched gas streams. For instance, fuel cells--a
promising alternative energy source--typically employ hydrogen as a
fuel for generating power. Many industrial processes also employ
hydrogen or hydrogen-enriched gas streams in a variety of fields
for the manufacture and production of a wide assortment of end
products. However, pure hydrogen is not available as a natural
resource in a form that can be readily exploited. As a
counter-example, natural gas, a hydrocarbon-based fuel, is
frequently found in large subterranean deposits that can be easily
accessed and transported once tapped. Nature does not provide such
deposits of hydrogen.
[0005] One way to overcome this difficulty is the use of "fuel
processors" or "reformers" to convert hydrocarbon-based fuels to a
hydrogen rich gas stream which can be used as a feed for fuel
cells. Hydrocarbon-based fuels, such as natural gas, liquid
petroleum gas ("LPG"), gasoline, and diesel, require conversion for
use as fuel for most fuel cells. Current art uses multi-step
processes combining an initial conversion process with several
clean-up processes. The initial process is most often steam
reforming ("SR"), autothermal reforming ("ATR"), catalytic partial
oxidation ("CPOX"), or non-catalytic partial oxidation ("POX"). The
clean-up processes are usually comprised of a combination of
desulfurization, high temperature water-gas shift, low temperature
water-gas shift, selective CO oxidation, or selective CO
methanation. Alternative processes include hydrogen selective
membrane reactors and filters.
[0006] However, safety issues can arise. Consider a hydrogen
fueling station for refueling fuel cell powered vehicles that
employs a fuel processor. Fuel processing involves pressures and
temperatures that, if not controlled properly, could damage the
equipment or create harmful conditions for the operators. Moreover,
depending on the nature of the fuel processor, both the reactants
reformed and the hydrogen produced can require careful control and
handling. The hydrogen produced by a fuel processor is also
typically stored under pressure until it can be dispensed, which
also needs appropriate controls. Thus, new and better control
strategies are desirable.
SUMMARY OF THE INVENTION
[0007] The invention comprises, in its various aspects and
embodiments, an apparatus and a method for use in controlling the
apparatus. The apparatus includes a hydrogen generator; at least
one of a compression unit, a storage unit, and a dispensing unit;
and a system controller. The system controller is capable of
monitoring the operation of the hydrogen generator and the
compression unit, storage unit, or dispensing unit at a system
level and shutting down at least one of hydrogen generator and the
compression unit, storage unit, or dispensing unit upon the
detection of a dangerous condition. The method includes monitoring
the generation of a hydrogen stream from a system level; monitoring
the at least one of a compression, a storage, and a dispensing of
the hydrogen gas stream from the system level in concert with
monitoring the hydrogen gas stream generation; and shutting down at
least one of the hydrogen gas stream generation and the
compression, the storage, or the dispensing upon the detection of a
dangerous condition at the system level.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] The invention may be understood by reference to the
following description taken in conjunction with the accompanying
drawings, in which like reference numerals identify like elements,
and in which:
[0009] FIG. 1 is a block diagram of one particular embodiment of an
apparatus, a hydrogen fueling station in the illustrated
embodiment, constructed and operated in accordance with the present
invention;
[0010] FIG. 2 illustrates one particular embodiment of a method
practiced in accordance with the present invention as a part of the
operation of the apparatus of FIG. 1;
[0011] FIG. 3 is a block diagram of one embodiment of the purified
hydrogen generator of the apparatus of FIG. 1;
[0012] FIG. 4 is a block diagram of one particular embodiment of
the fuel processor of the purified hydrogen generator in FIG.
3;
[0013] FIG. 5 is a block diagram of one particular embodiment of
the compression, storage, and dispensing unit of FIG. 1;
[0014] FIG. 6 illustrates one particular embodiment of a control
system implemented in accordance with the present invention;
[0015] FIG. 7A and FIG. 7B conceptually illustrate a computing
apparatus as may be used in the implementation of the embodiment of
FIG. 6;
[0016] FIG. 8 depicts one particular embodiment of the control
system of FIG. 6 for use in locally controlling the fuel processor
first shown in FIG. 3;
[0017] FIG. 9 illustrates an architectural hierarchy of a subsystem
manager for the control system first shown in FIG. 8 in accordance
with the present invention;
[0018] FIG. 10 illustrates a combinatorial strategy for controlling
the shift bed temperature of the reformer in FIG. 4;
[0019] FIG. 11 is a block diagram of one particular embodiment of
the apparatus in FIG. 1;
[0020] FIG. 12A-FIG. 12F provide additional detail on the structure
of the hydrogen generator of FIG. 4 and, in particular,
approximations of the locations for the parameters of its operation
being directly monitored from a system level; and
[0021] FIG. 13A and FIG. 13B conceptually illustrate a computing
apparatus as may be used in the implementation of one particular
embodiment of the present invention.
[0022] While the invention is susceptible to various modifications
and alternative forms, the drawings illustrate specific embodiments
herein described in detail by way of example. It should be
understood, however, that the description herein of specific
embodiments is not intended to limit the invention to the
particular forms disclosed, but on the contrary, the intention is
to cover all modifications, equivalents, and alternatives falling
within the spirit and scope of the invention as defined by the
appended claims.
DETAILED DESCRIPTION OF THE INVENTION
[0023] Illustrative embodiments of the invention are described
below. In the interest of clarity, not all features of an actual
implementation are described in this specification. It will of
course be appreciated that in the development of any such actual
embodiment, numerous implementation-specific decisions must be made
to achieve the developers' specific goals, such as compliance with
system-related and business-related constraints, which will vary
from one implementation to another. Moreover, it will be
appreciated that such a development effort, even if complex and
time-consuming, would be a routine undertaking for those of
ordinary skill in the art having the benefit of this
disclosure.
[0024] FIG. 1 illustrates one particular embodiment of an apparatus
100 constructed and operated in accordance with the present
invention. The apparatus 100 functions as a hydrogen fueling
station. The apparatus 100 comprises a hydrogen generator, e.g., a
purified hydrogen generator ("PHG"), 102, a compression, storage,
and dispensing unit ("CSD") 104, and a system controller 106. The
PHG 102 produces a purified hydrogen gas stream 108 from a fuel
110. Note that the term "purified" does not necessarily imply that
the pure hydrogen gas stream 108 is 100% hydrogen. As those in the
art having the benefit of this disclosure will appreciate, the
purified gas stream 108 will contain some minimal amount of
impurities. The amount will be implementation specific. In the
illustrated embodiment, the purified hydrogen gas stream 108 is
equal to or greater than about 99.8% hydrogen. As the name implies,
the CSD 104 compresses the purified hydrogen gas stream 108, stores
it, and then dispenses it on demand. The dispensed hydrogen 112 can
then be used to, e.g., refuel vehicles powered by fuel cells.
However, the dispensed hydrogen 112 may be used for other
purposes.
[0025] The system controller 106 is capable of monitoring the
operation of the PHG 102 and the CSD 104 and shutting down at least
one of them upon the detection of a dangerous condition. More
particularly, the system controller 106 performs the method 200,
shown in FIG. 2. The system controller 106 monitors (at 203) the
generation of a purified hydrogen stream 108 from a system level.
The system controller 106 also monitors (at 206) at least one of a
compression, a storage, and a dispensing of the purified hydrogen
gas stream 108 from the system level in concert with monitoring the
purified hydrogen gas stream generation. In the illustrated
embodiment, the system controller 106 actually monitors all three
of the compression, storage, and dispensing. The system controller
106 then shuts down (at 209) at least one of the purified hydrogen
gas stream generation and the compression, the storage, or the
dispensing upon the detection of a dangerous condition at the
system level.
[0026] To further an understanding of the present invention, and to
illuminate various aspect of the present invention that may be
practiced in alternative embodiments, additional details on the
construction and operation of the apparatus 100 will now be
presented. The construction of the PHG 102 is illustrated in FIG.
3-FIG. 4. FIG. 5 depicts an implementation of the CSD 104. FIG.
6-FIG. 11 illustrate a control technique for the hydrogen generator
300.
[0027] FIG. 3 depicts one particular embodiment of the PHG 102 of
the apparatus 100 in FIG. 1. The PHG 102 includes a hydrogen
generator 300 fed the fuel 110. The hydrogen generator 300 reforms
the fuel 110 to produce a reformate 303, which is a hydrogen
enriched gas stream. In the illustrated embodiment, the reformate
303 is 40% hydrogen. The hydrogen generator 300 is, in the
illustrated embodiment, a fuel processor. A compressor 306
compresses the reformate 303 and provides it at a predetermined
pressure to a hydrogen purifier 309. The hydrogen purifier 309 is,
in this particular embodiment, a pressure swing adsorption ("PSA")
unit. The hydrogen generator 300, the compressor 306, and the
hydrogen purifier 309 operate under the direction of a local,
automated control system 312, represented by a computing apparatus
315.
[0028] The design of the hydrogen generator 300, and the reforming
process it implements, will depend to a large degree on the fuel
110 input to the hydrogen generator 300 and the end use to which
the reformate 303, once purified, will be put. The fuel in the
illustrated embodiment is natural gas, but may be some other type
of hydrocarbon. The fuel 110 may be liquid or gas at ambient
conditions as long as it can be vaporized. As used herein the term
"hydrocarbon" includes organic compounds having C--H bonds capable
of producing hydrogen from a partial oxidation or steam reforming
reaction. The presence of atoms other than carbon and hydrogen in
the molecular structure of the compound is not excluded. Thus,
suitable fuels include, but are not limited to hydrocarbon fuels
such as natural gas, methane, ethane, propane, butane, naphtha,
gasoline, and diesel fuel, and alcohols such as methanol, ethanol,
propanol, and the like.
[0029] The design of the hydrogen generator 300 will be a function
of a number of factors, including the fuel 110 to be used and the
composition of the reformate 303. As mentioned above, the hydrogen
generator 300 of the illustrated embodiment is a fuel processor.
Fuel processors are well known to the art and any suitable fuel
processor design known to the art may be used to implement the
hydrogen generator 300. One such design is discussed more fully
below relative to FIG. 4. Note, however, that technologies other
than fuel processing are known by which the fuel 110 may be
converted to a hydrogen rich gas stream. One such exemplary,
alternative technology is an electrolyzer. Thus, the hydrogen
generator 300 is but one example of a means by which the fuel 110
may be reformed and other means may be employed in alternative
technologies.
[0030] Similarly, the design of the hydrogen purifier 309 will be
function of factors such as the composition of the reformate 303
and the requirements, such as output pressure and purity, for the
output purified hydrogen 108. The compressor 306 is selected to
accommodate the output pressure of the hydrogen generator 303 and
the input pressure of the hydrogen purifier 309. Also as mentioned
above, the hydrogen purifier 309 of the illustrated embodiment is a
PSA unit. PSA units are well known to the art and any suitable PSA
unit design known to the art may be used to implement the hydrogen
purifier 309. Note, however, that technologies other than pressure
swing adsorption are known by which the reformate 303 may be
purified. One such exemplary, alternative technology is to use
hydrogen-selective membranes such as are known in the fuel
processing art for separating hydrogen from impurities in a
hydrogen rich stream. Thus, the hydrogen purifier 309 is but one
example of a means by which the reformate 303 may be purified and
other means may be employed in alternative technologies.
[0031] As previously mentioned, the hydrogen generator 300 provides
a hydrogen-rich effluent stream, or "reformate," as indicated by
the graphic 303 to the hydrogen purifier 309. The reformate 303, in
the illustrated embodiment, includes hydrogen and carbon dioxide
and can also include some water, unconverted hydrocarbons, carbon
monoxide, impurities (e.g., hydrogen sulfide and ammonia) and inert
components (e.g., nitrogen and argon, especially if air was a
component of the feed stream). Note, however, that the precise
composition of the reformate 303 is implementation specific and not
material to the practice of the invention.
[0032] FIG. 4 illustrates one particular embodiment of the hydrogen
generator 300 of the illustrated embodiment. The hydrogen generator
300 is, in the illustrated embodiment, a "fuel processor," or
"reformer," i.e., an apparatus for converting hydrocarbon fuel into
a hydrogen rich gas. The term "fuel processor" shall be used
herein. In the embodiment illustrated herein, the hydrogen
generator 300 is a compact processor for producing a hydrogen rich
gas stream from a hydrocarbon fuel. However, other fuel processors
may be used in alternative embodiments. The hydrogen generator 300
comprises several modular physical subsystems, namely: [0033] an
autothermal reformer ("ATR") 410 that performs the
oxidation-reduction reaction that reforms the fuel 110 into the
reformate 303; [0034] an oxidizer ("Ox") 414, which is an anode
tailgas oxidizer ("ATO") in the illustrated embodiment, that
preheats water 416, fuel 110, and air 418 for delivering a heated
fuel mixture, or "process feed stream," 420 delivered to the ATR
410; [0035] a fuel subsystem 422, that delivers an input fuel 110
to the oxidizer 414 for preheating and inclusion in the process
feed stream 420 delivered to the ATR 410; [0036] a water subsystem
424, that delivers the water 416 to the oxidizer 414 for conversion
to steam and inclusion in the process feed stream 420 delivered to
the ATR 410; [0037] an air subsystem 426, that delivers air 418 to
the oxidizer 414 for inclusion in the process feed stream 420
delivered to the ATR 410; and [0038] a thermal subsystem 428, that
controls temperatures in the operation of the ATR 410 by
circulating a water 416 therethrough. Particular embodiments of
these subsystems are disclosed more fully below relative to FIG.
12A-FIG. 12F. The fuel subsystem 422, water subsystem 424, air
subsystem 425, and thermal subsystem 428 may be implemented in any
manner known to the art suitable for achieving the operational
characteristics of the oxidizer 414 and ATR 410.
[0039] In some embodiments, the water gas shift of the ATR 210
employs non-pyrophoric shift catalyst(s), not shown. Non-pyrophoric
shift catalysts are those that typically do not increase in
temperature more than 200.degree. C. when exposed to air after
initial reduction. Non-pyrophoric shift catalysts may be based on
precious metals, e.g., platinum or non-precious metals, e.g.,
copper. A commercially available non-pyrophoric shift catalyst
suitable for use with the present invention is the SELECTRA
SHIFT.TM. available from Engelhard Corporation, Iselin, N.J.
However, other suitable non-pyrophoric shift catalysts may be
used.
[0040] During reforming operations of ATR 210, reformate and
optionally additional steam are directed through the shift catalyst
bed. Care should be taken to assure that liquid water does enter
the shift bed as liquid water will coat and potentially degrade the
catalyst. The shift reaction temperature is maintained at a
temperature below about 300.degree. C. The shift catalyst can
withstand transient temperatures that exceed such temperatures for
short periods of time of less than about 60 minutes, preferably
less than about 45 minutes, and more preferably less than about 30
minutes. However, even during such transient periods, the reaction
temperature should be less than about 400.degree. C., preferably
less than about 375.degree. C. and more preferably less than about
350.degree. C. Should the shift catalyst be subjected to
over-temperature conditions for an extended period of time, the
activity of the catalyst can irreversibly change to favor a
methanation reaction.
[0041] The shift catalyst requires regeneration in order to
maintain its activity. Regeneration of the shift catalyst can be
achieved through oxidation. Specifically, the flow of steam to the
reformer and to the shift catalyst bed is interrupted so that only
air flows through the shift bed. After the reactor has been purged,
oxidation of the shift catalyst bed is allowed to proceed.
Regeneration of the catalyst bed through oxidation can be allowed
to proceed more slowly at lower temperatures, e.g. by maintaining
the shift bed at a temperature about 220.degree. C. overnight, or
may be driven more quickly at higher temperatures, e.g., by
maintaining the shift bed at a temperature up to about 400.degree.
C. for about hour or more. During regeneration, care should be
taken to ensure that neither liquid water nor steam flow through
the shift catalyst bed.
[0042] FIG. 5 illustrates one particular embodiment of the CSD 104
of FIG. 1. The CSD unit 104 includes a compression unit 500, a
storage unit 503, and a dispensing unit 506. The compression unit
500 receives the purified hydrogen 108 from the PHG 102 for storage
in the storage unit 503. The purified hydrogen 108 is stored under
pressure until dispensed via the dispensing unit 506. The operation
of the CSD 104 is controlled by a local, automated control system
509, represented by the computing apparatus 512. The CSD 104 may be
any CSD known to the art.
[0043] Both the PHG 102 and the CSD 104 include a local
controller--namely, the local control system 312, shown in FIG. 3,
and the local control system 509, shown in FIG. 5. These local
control systems 312, 509 may use conventional control strategies
commonly known to the art. In the illustrated embodiment, the local
control system 509 of the CSD 104 does, in fact, employ
conventional control strategies. However, the PHG 102 does not.
[0044] FIG. 6 illustrates one particular embodiment of a control
system 600 designed, built, and operated in accordance with the
present invention. This particular control system is more fully
disclosed in U.S. application Ser. No. 10/407,488, entitled
"Architectural Hierarchy of Control for a Fuel Processor," filed
Apr. 19, 2003, in the name of the inventors Vesna R. Mirkovic et
al., and commonly assigned herewith. Pertinent portions will now be
reproduced to further an understanding of selected aspects of the
present invention.
[0045] The control system 600 comprises a master control manager
602, and a plurality of physical subsystem managers 604. The number
of subsystem managers 604 is not material to the invention.
Accordingly, FIG. 6 illustrates N subsystem managers 604,
designated SUBSYSTEM MANAGER.sub.0-SUBSYSTEM MANAGER.sub.N. In
theory, the number N may be any number, although those skilled in
the art having the benefit of this disclosure will appreciate that
certain practical limitations will arise from implementation
specific details. Nevertheless, the number N of subsystem managers
604 is not material to the practice of the invention.
[0046] The control system 600 is largely software implemented on a
computing apparatus, such as the rack-mounted computing apparatus
312 is illustrated in FIG. 7A and FIG. 7B. Note that the computing
apparatus 312 need not be rack-mounted in all embodiments. Indeed,
this aspect of any given implementation is not material to the
practice of the invention. The computing apparatus 312 may be
implemented as a desktop personal computer, a workstation, a
notebook or laptop computer, or even an embedded processor.
[0047] The computing apparatus 312 illustrated in FIG. 7A and FIG.
7B includes a processor 705 communicating with storage 710 over a
bus system 715. The storage 710 may include a hard disk and/or
random access memory ("RAM") and/or removable storage such as a
floppy magnetic disk 717 and an optical disk 720. The storage 710
is encoded with a data structure 725 storing the data set acquired
as discussed above, an operating system 730, user interface
software 735, and an application 765. The user interface software
735, in conjunction with a display 740, implements a user interface
745. The user interface 745 may include peripheral I/O devices such
as a key pad or keyboard 750, a mouse 755, or a joystick 760. The
processor 705 runs under the control of the operating system 730,
which may be practically any operating system known to the art. The
application 765 is invoked by the operating system 730 upon power
up, reset, or both, depending on the implementation of the
operating system 730. In the illustrated embodiment, the
application 765 includes the control system 600 illustrated in FIG.
6.
[0048] Thus, at least some aspects of the present invention will
typically be implemented as software on an appropriately programmed
computing device, e.g., the computing apparatus 312 in FIG. 7A and
FIG. 7B. The instructions may be encoded on, for example, the
storage 710, the floppy disk 717, and/or the optical disk 720. The
present invention therefore includes, in one aspect, a computing
apparatus programmed to perform the method of the invention. In
another aspect, the invention includes a program storage device
encoded with instructions that, when executed by a computing
apparatus, perform the method of the invention.
[0049] Returning now to FIG. 4, in the illustrated embodiment, each
of the ATR 410, oxidizer 414, fuel subsystem 422, water subsystem
424, air subsystem 426, and thermal subsystem 428 constitutes a
physical subsystem controlled by one of the subsystem managers 604.
Thus, one particular implementation of the control system 600 for
use with the particular hydrogen generator 300 in FIG. 4 is shown
in FIG. 8 comprises: [0050] a master control manager 802 that
manages the control of the hydrogen generator 300 through the
subsystem managers: [0051] a fuel subsystem manager 804 that
controls the delivery of fuel to the ATO 414 for mixing into the
process feed stream delivered to the ATR 410; [0052] a water
subsystem manager 806 that controls delivery of water to the ATO
414 for mixing into the process feed stream delivered to the ATR
410; [0053] an air subsystem manager 808 that controls delivery of
air to the ATO 414 for mixing into the process feed stream
delivered to the ATR 410; [0054] an ATO subsystem manager 810 that
controls the mixing of steam, fuel, and air to create a fuel
mixture delivered as a process feed stream to the ATR 410; [0055]
an ATR subsystem manager 812 that controls the oxidation-reduction
reaction in the ATR 410 that reforms the fuel 110 input to the
hydrogen generator 300 into a reformate 303; [0056] a thermal
subsystem manager 814 that controls temperatures in the operation
of the ATR 410 through the thermal subsystem 428. [0057] a
compressory PSA subsystem manager 815 that controls the operation
of the compressor 306 and the Hydrogen purifier 309. Thus, each of
the subsystem managers 804-814 controls the operation of a
respective physical subsystem 410, 414, 422, 424, 426 and 428.
[0058] The control system 800 further includes additional layers
that contribute to its modularity in a hierarchical fashion. More
particularly, the control system 800 includes a hardware-dependent
layer 816 and a "compatibility" layer 818. Aspects of the control
functionality that are hardware-dependent are segregated into the
hardware-dependent layer 816. For example, referring to FIG. 4, to
increase the flow of fuel 110 to the oxidizer 414, one or more
control valves are opened. A control signal (not shown) is
transmitted from the control system 800 to the actuator (also not
shown) of the control valve(s), and the characteristics of this
signal are hardware dependent. The functionality of actually
generating and transmitting this control signal is segregated into
the hardware-dependent layer 816. Thus, if the hardware in, for
example, the fuel subsystem 422 is changed out from one model to
another, then only the hardware-dependent layer 816 needs to be
amended.
[0059] The compatibility layer 818 converts instructions issued by
the subsystem managers 804-815 so that they are compatible with the
hardware of the hydrogen generator 300. For instance, one subsystem
manager 804-815 may request an event using a particular unit of
measurement. The hardware needed to implement the request may take
instructions in a second unit of measurement. The compatibility
layer 818 will translate the instruction issued by the subsystem
managers 804-815 in the first unit of measurement to the second
unit of measurement employed by the hardware so it can be
implemented by the hardware-dependent layer 816.
[0060] The illustrated embodiment of the control system 800
furthermore includes a diagnostic layer 820 that also contributes
to its modularity in a hierarchical fashion. Each of the subsystem
managers 804-815 monitors its respective physical subsystem 410,
414, 422, 424, 426, and 428 for error conditions. More
particularly, the subsystem managers 804-815 monitor for "shutdown"
conditions, i.e., error conditions sufficiently important they
warrant shutting down the hydrogen generator 300. The error
conditions detected by the subsystem managers 804-815 are reported
to the master control manager 802 through the diagnostic layer
820.
[0061] Each of the subsystem managers 804-815 also embodies a
modular internal structure 900 conceptually illustrated in FIG. 9.
Each of the subsystem managers 804-815 employs this modular
internal structure 900 to conduct its management of the respective
physical subsystem 410, 414, 422, 424, 426, 428, 300, 306 and 309.
Each of the subsystem managers 804-815 includes: [0062] an
information exchange module 905 through which the particular
subsystem manager 804-815 determines the feasibility of
implementing events requested by other subsystem managers 804-815
through the master control manager 802 and identifies the actions
for implementing requested events; [0063] a diagnostic module 910
that communicates with the diagnostic layer 820 through the
information exchange module 905 to report error conditions; [0064]
a physical module 915 with which the information exchange module
905 consults to identify the actions for implementing requested
events and with which the diagnostic module communicates to obtain
information regarding error conditions; and [0065] a control module
920 with which the physical module 915 consults to determine which
actions are to be taken to implement a requested event and through
which communicates with the hardware-dependent layer 816 through
the compatibility layer 818 to obtain the information for such
determination. In alternative embodiments of the control system 800
omitting the diagnostic layer 820, the diagnostic module 910 may be
omitted from the subsystem managers 804-815.
[0066] Returning to FIG. 8, in the illustrated embodiment, the
subsystem managers 804-815 cooperate with each other by
communicating requests from their information exchange modules 905
through the master control manager 802. For instance, consider a
situation in which the oxidizer 414, first shown in FIG. 4, senses
a drop in pressure in the feed from the fuel subsystem 422, also
first shown in FIG. 4. The ATO subsystem manager 810 may request
that the supply of fuel increase. In the parlance of the
illustrated embodiment, a fuel increase would be an "event." The
ATO subsystem manager 810 issues the request through its
information exchange module 905, shown in FIG. 9, which
communicates the request to the master control manager 802. The
master control manager 802 forwards the request to the appropriate
physical subsystem manager--the fuel subsystem manager 804, in this
case.
[0067] The fuel subsystem manager 804 receives the request via its
own information exchange module 905, which checks to see if it is
in the proper operational state (discussed further below) to
implement the request. The fuel subsystem manager 804 then
implements the requested event if it is permissible and feasible.
The information exchange module 905 instructs the physical module
915 to implement the requested event. The information exchange
module 905 queries the controller module 920 about which actions
need to be taken. The information exchange module 905 then informs
the physical module 915 of those actions that need to be taken. The
physical module 915 then issues such an instruction to the hardware
actuator (not shown) through the hardware dependent layer 816 via
the compatibility layer 818.
[0068] The subsystem managers 804-815 can use conventional control
strategies to control the startup and operation their respective
subsystems. However, in the illustrated embodiment, the ATR
subsystem manager 812 employs a combinatorial control strategy to
control the shift reaction temperature. This control strategy is
more fully disclosed in U.S. application Ser. No. ______, entitled
"Combinatorial Control Strategy for Fuel Processor Reactor Shift
Temperature Control," (Atty. Docket No. 2098.001300/T-6433), filed
on an even date herewith in the name of the inventors Hongqiao Sun,
et al., and commonly assigned herewith. Pertinent portions will now
be reproduced.
[0069] FIG. 12F conceptually depicts one particular implementation
of the ATR 410. The ATR 410 may be implemented with any suitable
design known to the art. The illustrated ATR 410 comprises several
stages 1201-1205, including several heat exchangers 1209 and
electric heaters (not shown). The reformer shift bed 1212, i.e.,
the sections 1201-1202, is functioning to perform the water gas
shift reaction which reduces CO concentration and increases H.sub.2
production rate.
[0070] Each of the heat exchangers 1209 receives temperature
controlled coolant (not shown) from the thermal subsystem 428,
shown in FIG. 4, over the lines REF.sub.1-REF.sub.3, respectively,
and returns it over the lines THERM.sub.4-THERM.sub.4,
respectively. The flow rate for the coolant in each line is
controlled by a respective variable speed (i.e., positive
displacement) pump 1215-1217. The pumps 1215-1217 are controlled by
the automated control system 312, shown in FIG. 3, by signals
received over the lines A.sub.1-A.sub.4, respectively. In
alternative embodiments, a single pump may supply coolant under
pressure over the lines REF.sub.1-REF.sub.4 and the flow rate may
be controlled by flow control valves such as the flow control valve
1218. Those in the art having the benefit of this disclosure will
appreciate that this figure is simplified by the omission of some
elements not pertinent to the present discussion. For example, the
heat exchangers mentioned above and various inputs and outputs to
the sections 1203-1205 have been omitted for the sake of clarity
and so as not to obscure the control technique under
discussion.
[0071] The shift bed 1212 also includes a plurality of sensors
T.sub.1-T.sub.4 disposed therein. The precise number of temperature
sensors T.sub.x is not material, although a greater number will
typically provide a finer degree of control. In the illustrated
embodiment, the temperature sensors T.sub.1-T.sub.4 are
thermocouples. The automated control system 312 uses the
temperature sensors T.sub.1-T.sub.4 to monitor actual temperatures
at various locations within the shift bed 1212. Temperature
detection points are selected based upon the structure of the
cooling/heating system and should be selected so that the measured
temperatures reflect true reaction temperatures rather than
localized temperatures adjacent the heat exchange coils 1209.
[0072] Note that the temperature sensors T.sub.1 and T.sub.2 both
measure temperature near the same heat exchanger 1209 in a detail
that is implementation specific. That particular heat exchanger
1209 includes only a single coolant input REF.sub.1. Most of the
temperature sensors T.sub.1-T.sub.4 measure temperature downstream
from a catalyst bed section containing a heat exchanger 1209.
T.sub.1 is supposed to read the temperature immediately downstream
from the uppermost catalyst bed (not shown). However, during
installation and shipping the bed can shift and settle so that
T.sub.1 is measuring an air temperature rather than a bed or
reaction temperature. Thus, a second sensor T.sub.2 is added to
monitor the upper section 1201 of the ATR 410. When T.sub.1 and
T.sub.2 are sensing different temperatures, the control system 106
takes the higher of the two temperatures. Typically, there usually
is only a minor difference between the two sensed temperatures.
[0073] Preheating and water cooling maintain the temperature in the
shift bed 1212 within a desired reaction temperature range. In
order to achieve this objective, in an enlarged shift reactor,
multiple heat exchange coils 1209 may provide localized temperature
control. In the illustrated embodiment, the elongated shift bed
1212 utilizes three different heat exchange coils 1209 for
controlling the temperature of the shift bed 1212. The reaction
temperature control strategy varies as a combination result of
H.sub.2 production rate, shift reaction stage, shift bed vertical
temperature gradient and the temperature detecting points in a
manner described more fully below. A robust shift temperature
control loop is developed for the reformer to generate stable and
high quality H.sub.2 product.
[0074] FIG. 10 conceptually illustrates a control loop 1000
employed by the illustrated embodiment in accordance with the
present invention. The settings for each of the variable speed
pumps 1215-1217 is controlled by a respective control loop 1000.
The control technique employs, in the illustrated embodiment, the
complete system modeling effect (the reformer as a whole, including
ATR section, ZnO section, shift section, production rate, etc.),
develops a dynamic PID control loop to the plant response, and
testing data are used to compensate the model offset to improve the
robustness of the controller.
[0075] More particularly, system modeling takes into account the
target hydrogen production rate based upon current flow rates,
upstream temperature profiles, reaction stage and shift bed
temperature gradient due to heat loss and exothermal reaction
effect. A system model for each section of the shift bed can be
generated from the reactions and conditions upstream, the
geometries of the reactor, the feed to the shift catalyst bed, and
the type of shift catalyst that is used, among other factors.
Various modeling techniques of this type are known to the art, and
any suitable modeling technique may be employed. The system
modeling is used to generate set points to be used for the
temperature control. These set points include the predicted
reformate composition, flow rate and temperature that will be
entering a particular shift bed section. Thus, the system modeling
generates a group of setpoints for the temperatures measured by the
temperature sensors T.sub.1-T.sub.4. The system modeling also
produces a set of results correlating, for example, the
temperatures that may be measured by the temperature sensors
T.sub.1-T.sub.4 and the H.sub.2 production rate of the ATR 410.
[0076] More particularly, the model (not shown) used by the
illustrated embodiment was developed using Aspen Plus and Aspen
Custom Modeler. These software packages are commercially available
from: TABLE-US-00001 Aspen Technology, Inc. Ten Canal Park
Cambridge, Massachusetts 02141-2201 USA Phone: +1-617-949-1000 Fax:
+1-617-949-1030 email: info@aspentech.com
However, other suitable modeling software known to the art may be
employed in alternative embodiments.
[0077] The model has both steady-state and dynamic capabilities.
The performance of the fuel processor 300 is estimated by the model
from thermodynamic parameters that result in a desired state at the
given temperature and pressure. Reaction conversions and
compositions are determined from either kinetic data available in
literature for such typical reactions or estimated from models
based on experiments conducted in the laboratory for specific
reactions. The desired H.sub.2 purity and flow rate for the
reformate 303 are specified and the model calculates natural gas
flow, air flow (calculated back from the optimum O.sub.2/C ratio),
and water flow (calculated back from the optimum Steam/Carbon
ratio).
[0078] The resulting temperature of the ATR 410 is calculated as
the adiabatic temperature rise resulting from minimizing the free
energy of the ATR reaction. The composition of reformate is
determined by the model (from thermodynamic and reaction parameter
estimations). Using this composition, the model then calculates the
desired speed needed for the end use from empirical
correlations.
[0079] For each of the measured temperatures T.sub.1-T.sub.4, the
ATR subsystem manager 812 determines a first component 1003 for a
setting adjustment 1006 for an actuator governing a measured
temperature 1009 in a reaction section of a reactor from the
measured temperature 1009 and a setpoint 1012 for the measured
temperature. The setpoint 1012 is determined as a part of the
modeled results discussed above. The measured temperature 1009 is
the temperature measured by the temperature sensor T.sub.x at the
point of interest in the shift bed 1212, shown in FIG. 12F, at
which the temperature sensor T.sub.x is disposed. In the
illustrated embodiment, the difference 1015 between the setpoint
1012 and the measured temperature 1009 is input to a
proportional-integral-derivative ("PID") controller 1018, such as
is known in the art. The output of the PID controller 1018 is the
first component 1003.
[0080] The ATR subsystem manager 812 also determines a second
component 1021 for the setting adjustment 1006 from a H.sub.2
production rate 1024 for the fuel processor 102. In the illustrated
embodiment, at least selected portions of the modeled results
previously discussed are tabulated in a form indexable by the
H.sub.2 production rate. Thus, the modeled results 1027 may be, for
instance, a look-up table wherein various setting adjustments for
the actuator are indexed by the H.sub.2 production rate to which
they correlate. Note that the modeled results 1027 are typically
generate a priori by modeling the operation of the hydrogen
generator 300 in a variety of operating scenarios to obtain this
information. Note also that the determination of the first and
second components 1003, 1021 may be performed in parallel or in
serial.
[0081] The ATR subsystem manager 812 then determines the setting
adjustment 1006 from the first and second components 1003, 1021. In
the illustrated embodiment, the first and second components 1003,
1021 are summed to obtain the setting adjustment 1006, although
alternative embodiments may use more sophisticated techniques for
the determination. The setting adjustment 1006 is then signaled to
the actuator over the line A.sub.y. Note that the setting
adjustment 1006 may be 0, i.e., no change is needed because the
measured temperature 1009 suitably matches the setpoint 1012.
However, at any given time, at least one of, and sometimes all of,
the first component 1003, the second component 1021, and the
setting adjustment 1006 will be non-zero.
[0082] Note that, in some circumstances, the first and second
components 1003, 1021 could work in opposite directions with one
telling a pump to increase flow and the other telling the pump to
decrease flow. Thus, in the illustrated embodiment, the two
components 1003, 1021 are not given equal weight in controlling the
coolant flow. Specifically, the H.sub.2 production rate and the
information from the look up table, i.e., the second component
1021, is the dominant component. The first component 1003 that is
derived from sensed temperatures 1009 and the setpoints 1012, is
used to fine tune the pump speed. By way of example, the second
component 1021 might instruct a given pump to operate at 50% of
capacity, while the first component focuses on the error and may
adjust the pump speed by .+-.5% of capacity.
[0083] Thus, the present invention admits wide variation in the
manner in which the local controllers--namely, the local control
system 312, shown in FIG. 3, and the local control system 509,
shown in FIG. 5--perform their function. The local control system
312, for instance, may employ conventional techniques rather than
those disclosed above relative to FIG. 6-FIG. 10. Conversely, the
local control system 509 might employ the techniques employed by
the local control system 312.
[0084] Note, however, that codes imposed by governing legal
authorities might warrant modification to the control strategy.
Consider the hydrogen fueling station 1100, shown in FIG. 11, which
is a variation on the apparatus 100, shown in FIG. 1, with like
parts bearing like numbers. FIG. 11 also shows individual signals
for the hydrogen fueling station 1100 to provide a more detailed
example of how the present invention works in this particular
embodiment.
[0085] In the illustrated embodiment, the system controller 106 is
a programmable logic controller ("PLC") complying with the Class 1,
Division 2, Group B National Electrical Code standard. Suitable
PLCs are known to the art, such as the SIMATIC series of PLCs
commercially available from Siemens AG, Munich, Federal Republic of
Germany. The system controller 106 includes a 24V power supply (not
shown) and is powered by an uninterruptible power supply ("UPS")
1103, designated as "UPS2", without any fuse of circuit breaker to
avoid arcing or sparking in the cabinet 318, shown in FIG. 3, in
which it is housed. The PHG 102 is powered by a second UPS 1104,
designated "UPS1", and a supply 1105 from a conventional
three-phase power grid (not shown).
[0086] The system controller 106 also receives a number of other
signals related to safety concerns. The hydrogen fueling station
1100 includes a number of emergency shutoff ("ESO", not shown)
switches whose outputs 1106 the system controller receives
directly. The hydrogen fueling station 1100 also includes a number
of gas sensors (not shown) positioned about the site at which it is
located. The outputs 1109 of these sensors are also received
directly by the system controller 106. The gas sensors may be
dedicated to sensing one or both of the natural gas used as the
fuel 110 or the hydrogen 108, 110.
[0087] The hydrogen fueling station 1100 also includes a separate
fire alarm control panel 1112. In addition to the gas sensors, the
hydrogen fueling station 1100 includes a plurality of flame sensors
and smoke alarms (neither of which are shown) distributed across
the site. The outputs 1115, 1118 of these sensors are output to the
fire alarm control panel 1112. In addition, the PHG 102 includes a
plurality of flame sensors (not shown) whose outputs 1121 are
output directly to the fire alarm control panel 1112. The fire
alarm control panel 1112 monitors the outputs 1115, 1118, 1121 and,
if smoke or a flame is detected, outputs an alarm over the line
1124 to the system controller 106. The alarm is also sent, in the
illustrated embodiment, directly to the local fire department.
[0088] The PHG 102 and the CSD 104 directly communicate with each
other as indicated by the graphic 1127. The PHG 102 notifies the
CSD 104 when it is ready to deliver the purified hydrogen 108. The
CSD 104 notifies the PHG 102 when the storage unit 503, shown in
FIG. 3, is at minimum capacity and when it is full. In the
illustrated embodiment, "minimum capacity" is 30% of the total
capacity. Thus, once the PHG 102 is ready, it supplies purified
hydrogen 108 to the CSD 104 until the storage unit 503 is full and
then stops the supply. When the CSD 104 has dispensed enough of the
purified hydrogen 108 such that the storage unit 503 is at less
than 30% capacity, it notifies the PHG 102. The PHG 102 then again
supplies purified hydrogen 108 until the CSD 104 signals that the
storage unit 503 is full.
[0089] The PHG 102 and the CSD 104 also communicate
bi-directionally with the system controller 106, as indicated by
the graphics 1130, 1133, respectively. However, the communications
between the PHG 102 and the system controller 106 and the CSD 104
and the system controller 106 differ. The differences arise
directly from the different control strategies employed by the
system controller 106 with respect to the PHG 102 and the CSD
104.
[0090] The system controller 106 communicates directly with the
local control system 509, shown in FIG. 5, of the CSD 104. The
system controller 106 monitors an output from the CSD 104, awaiting
notification of a fault in the CSD 104. If the system controller
106 receives such a notification, then it issues a command to the
CSD 104 to shut down. All monitoring of local conditions within the
CSD 104 is performed by the local control system 509. The system
controller 106 therefore only monitors conditions within the CSD
104 indirectly, i.e., through the filter of the operation of the
local control system 509.
[0091] Conversely, the system controller 106 monitors the operation
of the PHG 102 by monitoring a plurality of parameters sensed
within the PHG 102. More particularly, as was discussed above, the
local control system 312, shown in FIG. 3, monitors operating
conditions within the PHG 102 in the first instance. The local
control system 312 performs this monitoring as a part of its
control function through the implementation of the hierarchical
control architecture 800, shown in FIG. 8. To this end, the PHG 102
includes a number of sensors, such as temperature and pressure
sensors (e.g., the temperature sensors T.sub.1-T.sub.4 in FIG. 10),
to monitor local operating conditions. To help illustrate the
manner in which these parameters are monitored, particular
implementations of the subsystems 410, 414, 422, 424, 426, 428 are
illustrated in FIG. 12A-FIG. 12F.
[0092] The monitored parameters for the illustrated embodiment are
set forth in Table 1. The system controller 106 can obtain the
individual parameters through the hierarchical control architecture
800 by, for instance, tapping the hardware dependent layer 816
through a counterpart to the compatibility layer 818.
Alternatively, the system controller 106 can receive the outputs of
the sensors directly. TABLE-US-00002 TABLE 1 Monitored Parameters
Condition Monitored/Associated Parameter Monitored Reference Action
Ox 414 Bed 1220, shown in T.sub.5, FIG. 12E Shutdown PHG 102 on
high FIG. 12E, Temperature temperature Ox 414 Inlet 1223, shown in
T.sub.6, FIG. 12E Shutdown PHG 102 on high FIG. 12E, Temperature
temperature (above electric heater) Reformer ATR 410 Inlet T.sub.7,
FIG. 12F Shutdown PHG 102 on high 1226, shown in FIG. 12F,
temperature Temperature Reformer Shift Temperature T.sub.4, FIG.
12F Shutdown PHG 102 on high temperature Reformer Outlet 1229,
T.sub.8, FIG. 12F Shutdown PHG 102 on high shown in FIG. 12F,
temperature Temperature Flammable Gas Detector - G.sub.1, FIG. 3
Shutdown PHG 102 on high level PHG 102 Flammable Gas Detector - G2,
FIG. 3 Shutdown PHG 102 on high level PHG 102 (above pan, not
shown) Flammable Gas Detector - G.sub.3, FIG. 3 Shutdown PHG 102 on
high level PHG 102 (near the compressor 306) PHG 102 Electrical
Cabinet P.sub.1, FIG. 3 Shutdown PHG 102 on electrical 318
Differential Pressure cabinet low pressure PHG 102 Hot and Cold
P.sub.2, FIG. 3 Shutdown PHG 102 on the hot and Cabinet 318
Differential cold cabinets low pressure Pressure Compressor 306
Suction P.sub.3, FIG. 3 Shutdown PHG 102 on high Pressure pressure
Compressor 306 2nd Stage T.sub.1, FIG. 12B Close XV-090 and
shutdown PSA Discharge Temperature and reformer compressor
Separator 1232 High High V.sub.1, FIG. 12B Shutdown the compressor
Level Separator 1235 High High V.sub.2, FIG. 12B Shutdown the
compressor Level Separator 1238 High High V.sub.3, FIG. 12B
Shutdown the compressor Level Digital output to PHG 102 PHG 102
Shut Down Output to PHG 102 to communicate Signal that an emergency
situation exists and PHG 102 must shutdown. Digital output to CSD
104 CSD Shut Down Output to CSD 104 to communicate Signal that an
emergency situation exists and CSD 104 must shutdown. Digital input
from CSD 104 CSD Fault Signal Input from CSD 104 that an emergency
exists in the CSD 104 and the rest of the facility must shutdown.
Digital signal inputs from the ESO#1-ESO#5 Manual Emergency Stop
Button in facility ESO buttons Signal the site CO Monitor - Hot
Cabinet T.sub.10, FIG. 3 Shutdown PHG 102 on high level 318 CO
Monitor G.sub.4, FIG. 3 Shutdown PHG 102 on high level Fire Alarm
Panel Fire Alarm Signal Signal indicating that a fire has been
detected and that the SIS needs to shutdown the facility. Station
Combustible Gas G.sub.1-G.sub.4, FIG. 5 Detection of any input will
cause a Detectors PHG 102 shutdown as well as a facility shutdown.
ATO 414, shown in FIG. 4 T.sub.11, FIG. 12E Shutdown PHG 102 on
high Inlet Temperature - Detection temperature of Flashback ATO
414, shown in FIG. 4, T.sub.12, FIG. 12E Shutdown PHG 102 on high
Inlet Temperature temperature UPS1 Under Voltage Relay UPS1 Fault
Signal Shutdown PHG 102 on Loss of UPS1 Voltage
[0093] Note, however, that the present invention admits variation
in this aspect in alternative embodiments. For instance, in some
embodiments, the system controller 106 may monitor conditions in
both the PHG 102 and the CSD 104 indirectly, i.e., through the
filters of the local control systems 312, 509, shown in FIG. 3,
FIG. 5, respectively. In other embodiments, the system controller
106 may directly monitor parameters sensed within the PHG 102 and
the CSD 104.
[0094] The system controller 106 is implemented in a computing
apparatus 1300 illustrated in FIG. 13A and FIG. 13B. The system
controller includes a processor 1305 communicating with storage
1310 over a bus system 1315. The storage 1310 may include a hard
disk and/or random access memory ("RAM") and/or removable storage
such as a floppy magnetic disk 1317 and an optical disk 1320. The
storage 1310 is encoded with a data structure 1325 storing the data
set acquired as discussed above, an operating system 1330, user
interface software 1335, and an application 1365. The user
interface software 1335, in conjunction with a display 1340,
implements a user interface 1345. The user interface 1345 may
include peripheral I/O devices such as a key pad or keyboard 1350,
a mouse 1355, or a joystick 1360. The processor 1305 runs under the
control of the operating system 1330, which may be practically any
operating system known to the art. The application 1365 is invoked
by the operating system 1330 upon power up, reset, or both,
depending on the implementation of the operating system 1330. In
the illustrated embodiment, the application 1365 implements the
method 200 illustrated in FIG. 2 and discussed above.
[0095] Note that at least some aspects of the present invention
will typically be implemented as software on an appropriately
programmed computing device, e.g., the computing apparatus 1300 in
FIG. 13A and FIG. 13B. The instructions may be encoded on, for
example, the storage 1310, the floppy disk 1317, and/or the optical
disk 1320. The present invention therefore includes, in one aspect,
a computing apparatus programmed to perform the method of the
invention. In another aspect, the invention includes a program
storage device encoded with instructions that, when executed by a
computing apparatus, perform the method of the invention.
[0096] Some portions of the detailed descriptions herein may
consequently be presented in terms of a software-implemented
process involving symbolic representations of operations on data
bits within a memory in a computing system or a computing device.
These descriptions and representations are the means used by those
in the art to most effectively convey the substance of their work
to others skilled in the art. The process and operation require
physical manipulations of physical quantities. Usually, though not
necessarily, these quantities take the form of electrical,
magnetic, or optical signals capable of being stored, transferred,
combined, compared, and otherwise manipulated. It has proven
convenient at times, principally for reasons of common usage, to
refer to these signals as bits, values, elements, symbols,
characters, terms, numbers, or the like.
[0097] It should be borne in mind, however, that all of these and
similar terms are to be associated with the appropriate physical
quantities and are merely convenient labels applied to these
quantifies. Unless specifically stated or otherwise as may be
apparent, throughout the present disclosure, these descriptions
refer to the action and processes of an electronic device, that
manipulates and transforms data represented as physical
(electronic, magnetic, or optical) quantities within some
electronic device's storage into other data similarly represented
as physical quantities within the storage, or in transmission or
display devices. Exemplary of the terms denoting such a description
are, without limitation, the terms "processing," "computing,"
"calculating," "determining," "displaying," and the like.
[0098] This concludes the detailed description. The particular
embodiments disclosed above are illustrative only, as the invention
may be modified and practiced in different but equivalent manners
apparent to those skilled in the art having the benefit of the
teachings herein. Furthermore, no limitations are intended to the
details of construction or design herein shown, other than as
described in the claims below. It is therefore evident that the
particular embodiments disclosed above may be altered or modified
and all such variations are considered within the scope and spirit
of the invention. Accordingly, the protection sought herein is as
set forth in the claims below.
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